VW Forschergruppe Experimentelle Evolution

Microorganisms are well known to readily enter into synergistic metabolic interactions with both other micro- and macroorganisms. The molecular prerequisites and selective conditions that favour the evolution of such cooperative interactions, however, remain poorly understood.

Hence, the main goal of our research is to answer the question: Why do organisms cooperate with each other? For this, we use the cooperative exchange of essential metabolites amongst two or more bacterial strains as an experimentally tractable model. By rigorously and systematically studying the molecularand ecological causes as well as the physiological and evolutionary consequences of a cooperative lifestyle, we aim at contributing to the development of a solid, empirically-based framework that allows to mechanistically predict the evolution of cooperative behaviours within microbial communities.

We address this fascinating research question by combining the methodological power of laboratory-based experimentswith recent advances in the fields of molecular microbiology and synthetic biology. First, specific ecological interactions between different microorganisms are synthetically engineered. The rationale of this design is based on a priori knowledge on the essential features of the focal interaction and its genetic implementation is guided by computational approaches. Second, theoretical models are being developed that provide testable hypotheses, which are then experimentally verified by exposing precisely defined microbial consortia to certain environmental conditions or selection pressures. These experiments are either performed on ecological time-scales, to monitor fitness-related shifts in the frequency distributions of the interacting populations, or in long-term evolution experiments, during which new genotypes arise by mutation and selection. Finally, post-hoc analyses are performed to study the underlying processes on a phenotypic, a physiological, and a genetic level. This laboratory-based approach is complemented by the study of natural microbial populations, in which we verify the general applicability of our findings.